The present invention relates to a method of separation and application of thin objects of a non-porous material or of a material of low porosity on a surface for biological and/or chemical reactions. The invention further relates to an apparatus for automatic separation and application of these objects and a package for the thin objects.
To determine various substances' ability of inhibiting or promoting growth of e.g. a microorganism, the substances are applied on a cultivation surface for the organism. This is accomplished by applying a carrier on the cultivation surface, on which carrier one or more substances are present in a predetermined and defined concentration pattern. Then the substances diffuse into the cultivation surface, e.g. agar, and the desired concentration pattern of substance(s) is achieved in the cultivation medium. After incubation of the cultivation medium with the substance and the microorganism to be tested, the result is normally read by measuring the inhibition zone. Various examples of how to perform this is illustrated i.a. in EP 0 157 071 and EP 0 444 390. These patents describe how to transfer a predetermined and defined concentration pattern of substances with the aid of thin, rectangular or square carriers having the substance(s) in the predetermined concentration pattern. These carriers, also called test strips, are very thin and made of a non-porous material or a material of low porosity, e.g. some kind of plastic material. They are applied manually on the cultivation surface as it has been difficult to achieve a more automated separation and application. So far these strips have been packed in stacks in blister packs of some suitable plastic material with smooth interior walls and of a dimension somewhat larger than that of the test strips. When picking up the uppermost strip from such a package it is difficult to pick up only that one without picking up a number of underlying strips due to adherence e.g. by static electricity.
U.S. Pat. No. 5,026,039 describes a method of feeding sheets from a stack of sheets in e.g. a copying machine using vacuum to lift the uppermost sheet. During the feeding a leaf spring is adapted in the paper path to separate the uppermost sheet from the subsequent sheet so that only one sheet is fed at the time.